GWS to M365
This Explain how to perform a Migration from Google Work Space(GWS) to Microsoft 365(M365).
M365 MIGRATIONS
Dhivagar Balaji
7/3/20264 min read
A Phased Approach to Google Workspace (GWS) to Microsoft 365 Migration
Organizations moving from Google Workspace to Microsoft 365 often seek better collaboration, security, compliance, and integration with the Microsoft ecosystem. However, migrating users, email, files, permissions, and collaboration workloads requires careful planning and execution.
A structured migration methodology helps ensure minimal business disruption, preserves data integrity, and provides users with a seamless transition to their new Microsoft 365 environment.
This guide outlines a proven three-phase approach for successfully migrating from Google Workspace to Microsoft 365.
Migration Approach
A successful migration should follow a phased methodology:
Pilot Migration – Migrate a small group of pilot users to validate the migration process, data integrity, and user experience.
Batch-Based Migration – Migrate users and workloads in planned production batches according to the migration schedule.
Batch Validation – Verify migrated data, permissions, and application functionality after each migration batch.
Delta Synchronization – Synchronize any changes made in Google Workspace after the initial migration.
Cutover – Switch mail flow, user access, and production services to Microsoft 365.
Post-Migration Support – Provide user assistance, issue resolution, and operational support following each migration wave.
Workloads That Can Be Migrated
A Google Workspace to Microsoft 365 migration typically includes the following workloads:
Gmail – User Mailboxes/Labels and folders/Emails/Attachments
Google Calendar – Calendar Events/Meeting Invitations/Shared Calendar (If supported)
Google Contacts – Personal Contacts/Contact Groups
Google Drive – My Drive Files/Folder Structure/Shared Files/File Permissions (If supported)
Shared Drives – Shared Drive Content /Folder Hierarchy/Permissions
Google Sites (Optional) - Site Content/Static Pages (depending on migration tool capabilities)
Google Groups - Distribution Lists/Group Memberships
Phase 1 – Pre-Migration Readiness
Objective
Prepare both the Google Workspace environment and Microsoft 365 tenant for migration.
Key Activities
Audit and Document the Existing Environment
Perform a complete assessment of the Google Workspace tenant, including:
User Accounts
Organizational Units (OUs)
Security Groups
Google Groups
Gmail Mailboxes
Google Drive Storage
Shared Drives
Google Calendar
Contacts
Google Sites
Third-Party Applications
Storage Consumption
User Licenses
Document mailbox sizes, Drive storage, sharing permissions, and identify inactive users or unnecessary data.
Prepare the Microsoft 365 Tenant
Verify that the Microsoft 365 environment is ready by:
Purchasing and assigning Microsoft 365 licenses
Verifying custom domains
Configuring Microsoft Entra ID
Creating user accounts
Configuring authentication methods
Setting up Exchange Online
Preparing OneDrive for Business
Configuring SharePoint Online
Preparing Microsoft Teams (if applicable)
Identity Planning
Determine how users will authenticate after migration.
This includes:
User provisioning
Password migration (if supported)
Single Sign-On (SSO)
Multi-Factor Authentication (MFA)
User Principal Name (UPN) mapping
Consolidation and Batch Planning
Organize all migration objects into manageable batches.
Migration objects include:
Users
Mailboxes
Google Drive users
Shared Drives
Google Groups
Shared Calendars
Create production batches based on:
Department
Geographic location
Business unit
Mailbox size
Business criticality
Pilot Migration Batch
Create a dedicated pilot batch consisting of a small number of representative users.
The pilot should include users with:
Large mailboxes
Shared Drives
Heavy Google Drive usage
Multiple calendars
Google Groups membership
Validate all migrated data before proceeding with production migration.
Production Batch Prioritization
Migrate larger mailboxes and users with significant Google Drive storage early in the project to reduce risk during the final migration window.
Phase 2 – Google Workspace to Microsoft 365 Migration
Objective
Migrate users and business data from Google Workspace into Microsoft 365.
Key Activities
Provision Users and Assign Licenses
Before migrating data:
Create user accounts
Assign Microsoft 365 licenses
Configure Exchange Online mailboxes
Enable OneDrive
Configure SharePoint
Assign Teams licenses (if required)
Verify that users can successfully authenticate.
Configure the Migration Tool
Configure the migration platform with both environments.
Typical configuration includes:
Connecting Google Workspace
Connecting Microsoft 365
Creating migration projects
Granting API permissions
OAuth authentication
User mapping
Domain mapping
Migration scheduling
Bandwidth throttling
Popular migration tools include:
Microsoft Migration Manager
BitTitan MigrationWiz
Quest On Demand Migration
AvePoint Fly
CloudM Migrate
Execute the Pilot Migration
Run the pilot migration using the predefined pilot users.
Validate:
Gmail – User Mailboxes/Labels and folders/Emails/Attachments
Google Calendar – Calendar Events/Meeting Invitations/Shared Calendar (If supported)
Google Contacts – Personal Contacts/Contact Groups
Google Drive – My Drive Files/Folder Structure/Shared Files/File Permissions (If supported)
Shared Drives – Shared Drive Content /Folder Hierarchy/Permissions
Google Sites (If Supported) - Site Content/Static Pages (depending on migration tool capabilities)
Google Groups - Distribution Lists/Group Memberships
Production Batch Migration
Once the pilot is approved, migrate production users according to the agreed migration schedule.
Each migration wave should include:
Gmail Mailboxes
Google Calendar
Contacts
Google Drive
Shared Drives
Google Groups
Google Sites (if applicable)
Where possible, perform pre-stage migrations several days before the production cutover to minimize downtime.
Batch Validation
After each migration batch, perform detailed validation.
Verify:
Exchange Online - Mailbox item count/Folder hierarchy/Calendar integrity/Contacts/Attachments
OneDrive - File count/Folder structure/File permissions/Sharing links
SharePoint - Document libraries/Metadata/Version history (where supported)
Microsoft Teams - Team creation/Channel access/Shared files/Membership
User Validation
Outlook connectivity
OneDrive synchronization
Teams sign-in
Mobile device access
Resolve all migration issues before proceeding to the next batch.
Delta Synchronization
Run incremental migrations to capture changes that occurred after the initial migration.
Synchronize:
Newly received Gmail messages
Calendar updates
Contact changes
Google Drive file modifications
Shared Drive updates
This minimizes downtime during the final cutover.
Production Cutover
Schedule the final migration during an approved maintenance window.
Typical cutover tasks include:
Stop Gmail mail delivery
Update MX records
Configure Microsoft 365 mail flow
Update SPF records
Enable DKIM
Configure DMARC
Redirect incoming email to Exchange Online
Verify Outlook connectivity
Validate Exchange Online mail flow
Test Teams functionality
Confirm OneDrive accessibility
Validate SharePoint access
Once all validation is complete, Microsoft 365 becomes the production environment.
Phase 3 – Validation & Google Workspace Decommissioning
Objective
Confirm the successful migration of all workloads and safely retire the Google Workspace environment.
Validation Activities
Conduct comprehensive validation across all migrated workloads.
Exchange Online
Mailbox validation
Calendar verification
Contacts
Email flow
OneDrive
File validation
Folder hierarchy
Sharing permissions
SharePoint Online
Sites
Libraries
Permissions
Metadata
Microsoft Teams
Team membership
Channels
Files
Meeting functionality
User Acceptance Testing (UAT)
Engage business users to verify:
Email functionality
Calendar synchronization
File accessibility
Shared documents
Collaboration tools
Mobile devices
Microsoft Office applications
Document and resolve any outstanding issues.
Application Integration Testing
Validate third-party applications previously integrated with Google Workspace, including:
CRM systems
HR platforms
Identity providers
Workflow automation
Backup solutions
Email gateways
Ensure all integrations now function correctly with Microsoft 365.
Security and Compliance Review
Complete a post-migration review to verify:
Multi-Factor Authentication (MFA)
Conditional Access policies
Microsoft Defender configurations
Data Loss Prevention (DLP)
Retention policies
Sensitivity labels
Audit logging
Compliance settings
Google Workspace Decommissioning
Once all users and workloads have been successfully migrated and validated:
Verify no active users remain
Confirm all required data has been migrated
Archive any remaining data (if required)
Remove unused Google Workspace licenses
Disable user accounts
Retire legacy services
Decommission the Google Workspace tenant according to organizational policies
Conclusion
A successful Google Workspace to Microsoft 365 migration depends on careful planning, phased execution, and thorough validation. By following a structured approach—starting with pilot migrations, progressing through batch-based production migrations, performing delta synchronization, and completing comprehensive post-migration validation—organizations can minimize disruption while ensuring data integrity and user productivity.
Whether migrating a few hundred users or an enterprise-scale environment, investing time in preparation, testing, and user communication significantly increases the likelihood of a smooth and successful transition to Microsoft 365.
